ALAMEDA (BCN) Already grappling with how to retain plastic it has collected at the Great Pacific Garbage Patch, a cleanup rig had another setback over the weekend and will be returning to port in Alameda sooner than expected.

During an inspection Saturday, crewmembers found that an end section of the cleanup's U-shaped boom had detached, Ocean Cleanup founder Boyan Slat said on the nonprofit's site.

There was no danger to the crew, the environment or marine traffic, and there's no risk that the rig would roll over, said Slat, a Dutch inventor who founded the cleanup project in 2013.

The Ocean Cleanup System 001, dubbed "Wilson," has had issues since it launched in September with retaining plastic collected in its 2,000-foot Pac-Man-shaped boom with a woven underwater skirt.

So far, plastic enters the system but isn't retained long enough to harvest it. Engineering and technology teams have been working on the problem since November.

Although disappointed, Slat said setbacks were inevitable with the "beta" technology.

"Although we would have liked to end the year on a more positive note, we believe these teething troubles are solvable, and the cleanup of the Great Pacific Garbage Patch will be operational in 2019," Slat said on the Ocean Cleanup site.

Being back in port at Alameda's former Navy base will afford the opportunity to address Wilson's plastic retention issue, Slat said.

Slat said it was too early to confirm what happened with the end section, but the crew believes that material fatigue and stress on the section caused a break.

The project aims clean up half the Pacific garbage patch five years.

Since it launched four months ago, Wilson amassed terabytes of data on the plastic capture process that can be used to make upgrades, Slat said.

A Maersk Transporter rig is also bringing back two tons of plastic -- discarded fishing ghost nets -- gathered over the past few weeks.

Discarded plastic -- fishing nets, bottle tops, containers and other junk -- have accumulated across a vast area about halfway between Hawaii and California.

The cleanup system was developed to corral the plastic, which is creating hazards for marine life and affecting the health of the world's oceans. The goal is to collect and remove larger pieces of plastic before they are broken down into more dangerous microplastics.

The system uses a tapered screen drifting about 10 feet underwater that's attached to floaters in a "Pac-Man" shape, to gather debris while allowing marine life to swim underneath the operation.

The nonprofit announced last year that it had raised $31 million since 2013, and counts Salesforce founder Marc Benioff and PayPal co-founder Peter Thiel among its major donors.

The Ocean Cleanup's team consists of 80 engineers, researchers and scientists, with headquarters in Rotterdam, the Netherlands. An assembly yard for its cleanup system was set up in February 2018 at the former Alameda naval air station, now known as Alameda Point.